How to use Appium Espresso with a Xamarin Forms app

I'm attempting to add some test automation to my XF app, but I'm having some difficulty as I've never used Appium before so I'm hoping that someone with experience may be able to help with my issues.

When I'm setting up my tests - if I set the "automationName" to be "UiAutomator2", then I can launch my app without problems and interact with the UI fine.

I need to do some tests with specific methods inside my app, but Appium only allows interaction with the UI. Doing some searching, I found that Appium contains an Espresso driver which is supposed to allow interaction with specific methods (this sounds exactly what I'm after).

The suggestion is to change the "automationName" from "UiAutomator2" to "Espresso" - the example I was going through in the Appium documentation was a simple test that just launched the app. It suggested that just by changing this setting, that the same test would work regardless.

I have created a simple test that just launches my app - this works fine with "UiAutomator2" but as soon as I change to "Espresso", my app doesn't launch.

The Appium server mentions not being able to find the signed .apk.

According to the documentation, this should all be working fine but as it isn't I'm guessing that there's something else that I need to do so I'm hoping that someone with experience with this will be able to help me get the tests to work.

I don't know whether I need to add a reference to Espresso somewhere in my XF app or if I need to build the .apk in a special way that will make it work.

Any advice or help on this matter would be grateful.